Fastening method



Sept- 24, l957 P. w. zlLLlAcus Er AL 2,807,083

- FASTENING METHOD Filed Jan. 51, 1955 2 sheets-sneer 1 ATToR/VEY Sept. 24, 1957 P. w. zlLLlAcus Er AL 2,807,083

FASTENING METHOD Filed Jan. 51, 1955 2 sheets-sheet 2 'f5 INVENTOR.

Patented Sept. 24,."1957 FASTENNGL'MTHOD 5 Applicationv January 31, 1955, Serial No. 484,968

2 Claims. (Cl. 29-510) This invention relates to an improved method of fastening, and more particularly to an improved fastening method involving the use of threaded bolts or studs.

In the manufacture of small industrial products, the product assembly frequently comprises a pair of opposing cover plates or enclosing members which are secured together by means of nuts land bolts or by means of nuts and studs which are attached to one of the cover plates `and extend through apertures in the opposing cover plate. Irremploying either of these means, it is necessary to fasten the nuts to each of the bolts or studs and to spin each fthese nuts individually on its respective bolt or stud to a point where the nut holds the assembly tightly together.V

An object of this invention is to provide an improved method for fastening together small assemblies.

Another object of this invention is to provide an improved fastening method Which employs threaded studs orbolts.

A further object of this invention is to provide an proved method of fastening an assembly wherein the securing means comprises a plurality of threaded'v studs or bolts disposed parallel to each other. y

A still further object of this invention is to provide an improved method for fastening an assembly including a plurality of studs or bolts wherein the fastening means 10 may be secured to all of the studs-or bolts simultaneously.

A still further object of this invention is to provide anV improved method of fastening an assembly including threaded studs or bolts wherein the necessity of spinning t nuts on the threaded members is eliminated. 45

A still further object of this invention involves animproved method of fastening anv assembly `including threaded studs or bolts ,wherein a fastening means can be accomplished by automatic methods.

In accordance with the present invention, an improved 50 fastening method involves the use of a tubular member which ts relatively snugly over the threaded portionof a 'threaded member. The threaded .member may-be i-nl theform of a bolt or screw which extendsthrough aperf` ture provided in two or more portions of an assembly-.55 which is to be fastened together, or it may be in the`form` of a stud which is rigidly attached to one of the portions of the assembly and extends through apertures provided in the remaining portions ofthe assembly whichlis .to beifastened together, lIn a preferred,form,wa plurality of threaded members Vextend parallel tocaehfother ,inl one direction and have threaded free ,ends extending out of the assembly on oneside thereof.4 lA tubular member is] placed4 over each, of thethreaded free ends. AThese tubuf larfinembers are v compressed against one side, of .the Y assembly while the opposite sideof the assembly, in-X cluding the heads of the bolts or screws if applicable, `is held yagainst vr'novem'ent.V ThisA compressingA force,V causes 7 the tubular members to collapse Vor accordion vragainst the l assembly and'to engage several vthreadsof each ofthe 70 threadedI members whereby. the assemblyfis ilo'cked tof"` getler. f t,

The novel features of the invention, as well as additional objects and advantages thereof, will be understood more fully from the following description when read in connection with the accompanying drawing, in which:

Figurel is a fragmentary sectional viewv of a tool in position to press an eyelet to fasten a transformer structure;

Figure la is a fragmentary sectional view illustrating the eyelet as it begins to collapse and accordion due to the pressure of the tool; k

Figure lb is a fragmentary sectionalview illustrating the eyelet completely collapsed and accordioned just prior to final compression by the tool;

Figure 2 is a view similar to Figure l wherein the eyelet has been compressed to form the equivalent of a nut; and

`Figure 3 is a view similar to Figure 1 wherein a simple tube provides the fastening member.

Referring in more detail to Figures 1 through 2 of the accompanying drawing, the present invention is exemplified in the assembling of a transformer and the fastening together of the assembly means of bolts and eyelets. A transformer assembly 11, illustrated in section, comprises a plurality of laminations 13, stacked adjacent each other and enclosed at either end by Aan end plate or an end shield 15. The ends plates 15 are a part of the 'transformer assembly and are made of any suit-v able material vwhich is harder than the material of the eyelets and which may be formed to provide a suitable casing for the transformer. *The end plates 15 are provided with apertures 17 dimensioned to receive bolts 19 and providing a small clearance between the apertures and the bolts. Apertures 21, provided in the laminations 13 to accommodate the bolts 19, are somewhat larger than the apertures 17 since the clearance between these apertures and bolts is not critical. f

A standard eyelet 23 of a pliable metal, such as brass, is placed over the end of each bolt 19 and engages the outer surface of the end plate 15. This eyelet comprises a relatively` long, thin-walled, substantially cylindrical portion 25 and a head portion 27 formed by a flaring outwardly-of one end of the V-cylindrical portion 25. v The end of the eyelet opposite kfrom the head portion 27 is tapered f inwardly to provide aportion-ZS ofreduced external diameter."- lt is this feature ofthe standard eyelet which makes it especially suitable for use in practicing the method of 'l the present invention. It is. desirable tomaintain a substantialportion of the eyelet outsidefof the aperture 17 sincethis-provides a larger amount of metal for engage-H' l ment with the bolt l19. It is also desirable that a. portion ofthe eyelet extend into theaperture 17. l` The aperture 17 then is-dimensionedto receive thereduced portion 23 ofv the eyelet. This Y aids in lcausing-the eyeletfmateriab to accordion while itis being compressed against the u'p,V` perend platelS to form ther fastener. A

Af'orming vtool 2 9 for compressing an eyelet 23 against the upper end plate 1 5 comprises ajdriving bar 31,which may be constructedY of ahardened steel bar having an outer diameter slightly larger thanthe maximum diam-l l eter of the y eyelet head .2.7.` .'Thisbar-is provided ,with a t cylindrical recess 33.extendingaxially.from itslower end and being sutliciently deep to.accommodate the ends of the bolts or studs againstwhich it compresses the eyelet. An annular shoulder.35 is provided -at a pointremoved lfrom the end .of theY bar.. A cylindrical sleeve 37 is slidably mountedover thedlow'er` end of Ythebar 3 1. The upper surface 39 ofthis sleeve opposes theshouldertSS of the Ybar 3 1 and a helical compression spring 41 is mounted on the bar, bearingagainst the'shoulder 35 and the surface'39`. v Apai'rof elongated slots 43-a`re disposed f longitudinally in opposite' sides 'of the sleeve liT'adjacentT the upper end of the sleeve. `A pin 45 extends diametri- 1 cally through the bar '31and isi-rigidly x'e'd to'f'thebar Q The'ends" of this pin 4'5J4 extend' out of the bar 31 and through `the slotsi43. By'thismearis the' sleeve" 37 i's" spl ported on the bar 31. The spring 41 will bias the sleeve 37 downwardly with respectto the driving bar 31 and in thisfdownw'ard position' thetlower surface 47 'ofthe'sle'eve- 37 extend somewhat' below the' end of 'the' driving bar 31'. The action'ofthe driving`bar'31' is-opposed'by an anvill or plate" 49 which engages the'heads of the bolts`1'9.

Referring now to Figures' la, lb and 2, it will be seen that when the bar 31 descends to axially compress the eyelet 2 3 against thetransfonner'maplate 15, the eyelet begins' tocolla'p'se orl accordion from its`- tapered end portion 28 upwardly. The apparent reason that the collapsin'g' b'egiiis'at the taperedendf'portion 2'8'is that there is already an annular bend in `the/eyelet, atl the upper end ofthetapered end portion 2S as shown in the drawings, andthe eyelet is thereforev presumably less resistant to deformation at` this poing In addition, a component of force is eXerted/upwardlyand inwardly against the tapered p rti on 2 by the upper edge of the end plate-aperture 17 This force ac ts to further bend or deform the eyelet at this point. As a result ofthis first bend,-the eyelet metal is deflected inwardly against the bolt-threads; Once-the rst-fold is formed at this end'of the eyelet, the ,folding progressesffrom this point since each bend or fold in one direction starts a bend or fold in the oposite direction. It will be understood, however, that the manner in which the accordion folds are formed does not materially effect the final form of the eyelet or the manner in which the eyelet engages the bolt 19. Since the eyeletis composedV of apliablemetal, the accordion folds which are formed inthe eyelet as it is axially compressed are confined tol an area immediately adjacent the`bolt 19 over which the eyelet has' been-placed. Asf the folds form, the'internall surfaces of the folds engage the surfaceofthe'bolt 19 due to the small'clearance'between the internallsurface'of the eyelet and the bolt. The'sefoldsdonot extend radially outwardly from thebolt tothe extent that they'interfere with'the'descending sleeve 37.

Thelower surface47 of thesleeve 37 engages the' end plater IS-b'efore thelvbar' 31 re'achesthe end of its downward' stroke. The sleeve 37 then maintainsV` the collapsedeyelet withinits' confines.' With continued downwardly movement: of the` b'ai 31,v the eyelet metal isI compressed andtends to expand radially' outwardly' and inwardly. Sincera'dial'expahsion' is4` now'limited byV the sleeve 3 7-, the:- g'reater' expansion' is directed inwardly against the bolt' 19 s'o that several threads' are securely engagedby the eyelet metal. Themetalof the eyelet 23 is formed effectively, thoughjnotactu'ally, into a solid'n'netallicv mass' 23v as' shown in Figure A2 As the bar 31continu'esto move downwardly, the'v sleeve 37 movesA u'pwardiy' rela' tive'to" thebar 31', this movement being'ag'ainst" the force! of the spring 41 and being" permitted by theV elongated' slots' 43'.

The inclusion of the sleeve 37 as a'part ofthe tool 29 is not essential tol the practice' of the present invention. The simple axially compressive force ontheeyelet, which tsclosely around the bolt, provides suflcientv engagement between the folds'o'f the' eyelet metal' and the bolt for some applications. However this' sleeve provides a practical means for assuring goodbinding' between the eyelet metal and the bolt, especially where a large amount of metal is compressed against the bolt.

Referring now to Figure 3' a fastening' method Visill'ustrated employing a plain, thin-walled, metallic vsleeve 6I' as the elementtobe compressed against a bolt 19. Since the sleeve 61 is not provided with a tapered portionas described above, the collapse ofthe sleeve will probably not follow the same pattern. Presumably, thecollapse-of thesleeve will start at-about th'ecenter of the sleevelsince.- the-stress would be greatest at this-point: The'foldingofthe-sleeve willthen progressineither directionfromthisf 4,. central point. When such a sleeve is compressed Athe formed" fastener is substantially similar to the fastener illustrated in Figure 2.

The method is again illustrated in the assembling of a transformer 11 comprising a plurality of laminations 13 and an end shield 15. The forming tool 29 is identical to that described theretoforeand comprises a driving bar 31 and a retaining sle'eve 37 axially movable relative to the drivin-g bar. Y

InAvFig'u'r'esjland 3"'ofthe" accompanying drawing, both the eyelet 23and the sleev'e 61 havebeen shown initially as resting largely on'toplv of the transformer" end plate; that is only a `small portion, if any, of the' tubular parts of these members extends into the aperture provided in the transformer end plate and through which the bolt extends. With this arrangement essentially all of the metal of the fastener element is available to be compressed against thethreads of thebolt and therefore more of the threads will be engaged by this metaltoform a stronger fastener.l Where fastener strength is not a prime consideration of the assembly-,that iswhere high strength is not required, the aperture-in the end transformer plate could be made largerf in*v relation to the dimensions of the bolt in `order toipermit'i a substantial portion of the eyelet' or other headed member to-exte'nd intov the aperture. With this-latter arrangement only the portionV of the fastener comprising the head would be compressed against the threaded portion of thebolt and'v therefore fewer threadswould'be engaged:A Thisfarrangement provides the advanf tage, however;I that the* size of the aperture' in the`end plate is much less critical thereby reducing fabricationv costs-forthe overall transformer assembly.

A brass eyelet applied in the manner illustrated'inFiguresfl andZ requires1 a force of- 375 poundsto stn'p'the eyeletfrmI-th'ebolt'. A'rreyelet'l applied `in thema'nnerde;

scribed immediately above, wherein only the 'head is'coll* lap'sedfagainstl-tlie bolts requires a force ofv as much-.as 150 pounds" tostrip thefeyeletv from' the bolt.v It will be ap? parent'ffiom the foregoing that af standard brass eyelet used in the Figures and 2 ofthe' accompanying dravi/iilg'v i'nrth'e" manner disclosed; herein provides a fastener'thati'is a's" effective 4as a1 steel nut 'from the standpoint' A Y cijing'A a structuralA p'a'rt byv a scurng'fdevi'c'e comprrsinga thread" member for inseitio'n through,anopeniiginlsaid structural part and a metallic` sleeve' to be engaged" with said threaded member, saidmethod c'oiiipiisi'n'g"v inserting said threaded member throughs'aid structural par'twhereby a portion of said threaded member projects from said'part, positioning a relatively'loh'g, thin-Wall, pliable, metallic sleeve over said threaded' memberp'rojecting from said opening in said Istructural part and in engagement with said `structural part a'tl said' opening, said sleeve havingV an inwardly tapered'end" portion dirnensioned to be partially received within said opening, said sleeve having an internal diame-v ter slightly larger than the external diameter of s-ai'd threadednember, nestraining said threadedY member from movement outofsaidopening-in-said structuralpart, and compressing: said sleeve againstsaid 'structural part with a simple axial nforce, said axialv forcefeffecting; the colv lapse of said/:sleeve into= folds; progressing; fromV the'- tapered end thereof and forcing the internal folds of said fasteners' asf'idi'sclosed" over the'useY of nuts is' sleeve into locking engagement with Isaid threaded member.

2. A method of securing a structural part by a securing device comprising a threaded member for insertion through an opening in said structural part and a metallic sleeve to be engaged with said threaded member, said method comprising inserting said threaded member through said structural part whereby =a portion of said threaded membzer projects from said part, positioning a relatively long, thin-walled, pliable, metallic sleeve over said threaded member projecting from said opening in said structural part and in engagement with said structural part at said opening, said sleeve having an inwardly tapered end portion dimensioned to be partially received within said opening, said sleeve having lan internal diameter slightly larger than the external diameter of said threaded member, restraining said threaded member from movement out of said opening in said structural part, compressing said sleeve against said structural part with a simple ,axial force, said axial force effecting the collapse of said lsleeve into folds progressing from the tapered end thereof and forcing the internal folds of said sleeve into locking engagement with said threaded member, and `additionally compressing said icollapsed 4and yfolded sleeve while limiting outward radial expansion of said sleeve whereby said sleeve is expanded inwardly to provide more intimate engagement of said sleeve with said threaded member.

References Cited in the file of this patent UNITED STATES PATENTS 1,447,520 Schade Mar. 6, 1923 1,639,511 Lefever Apr. 16, 1927 1,852,297 Gelpcke Apr. 5, 1932 1,905,730 McIntosh et al Apr. 25, 1933 2,465,654 Millard Mar. 29, 1949 2,535,403 Froggatt Dec. 26, 1950 2,542,376 Torresen Feb. 20, 1951 2,639,832 Bergstrom May 26, 1953 

